A collector system of the type with which the present invention is concerned is referred to as a Fresnel reflector system and, depending upon its configuration, may be considered as an analogue of a parabolic dish or a linear parabolic trough. When configured as an analogue of a parabolic trough, the collector system comprises receivers which are supported by vertical masts and which are orientated or arrayed to form a linearly extending target. The reflectors are positioned slightly above ground level and are arrayed over an area that is selected to provide reflection of radiation toward the target receivers. The arrayed reflectors are orientated to reflect radiation toward one target, and the reflectors are pivotably mounted and coupled to provide for synchronised single-axis tracking.
The above described Fresnel reflector system permits the use of a large scale target and provides for low construction costs relative to those that would be incurred in equivalent size parabolic trough or dish collector systems. However, a problem that is inherent in the use of ground arrayed reflectors is that shading occurs as a consequence of radiation blockage.
A solution to this problem is disclosed in International Patent Application No. PCT/AU96/00177, dated Mar. 28 1996, lodged in the name of The University of Sydney as assignee of the present Inventor and subsequently assigned to the present Applicant. The referenced International Application has been published under number WO96/30705, and it discloses a collector system which comprises at least one group of arrayed reflectors and at least two target receiver systems associated with the or each group of reflectors. Individual reflectors within the or each group are normally orientated toward one or the other of the associated receiver systems, and at least some of the reflectors within the or each group are pivotable to an extent such that they may be re-orientated to shift the direction of reflected radiation from one to the other of the receiver systems.
In use of the system as disclosed in the referenced publication, a determination is made from time-to-time as to which reflectors should be orientated toward the respective receiver systems for the purpose of minimising shading, and individual reflectors (or sub-groups of the reflectors) are pivoted to meet the orientation requirements.
However, having developed the collector system as disclosed in the referenced International Patent Application in an attempt to achieve optimum collector efficiency, it has since been determined by the Inventor that near-optimum performance may be achieved by establishing two sub-groups of reflectors, by orientating all of the reflectors within the respective sub-groups toward respective ones of the receiver systems, and by pivoting a majority at least of the reflectors through the same angle whilst maintaining orientation of the reflectors within the respective sub-groups toward the respective ones of the receiver systems.